Synthesis, Rhodium Complexes and Catalytic Applications of a New Water-Soluble Triphenylphosphane-Modified β-Cyclodextrin

A new triphenylphosphane based on a beta-cyclodextrin skeleton (PM-beta-CD-OTPP) was synthesized. This ligand can be dispersed in water by using the nanoprecipitation method. Transmission electron microscopy and NMR spectroscopy showed that PM-beta-CD-OTPP is aggregated in water and forms a stable dispersion. Its aqueous solubility can be dramatically increased in the presence of selected water-soluble guests by formation of inclusion complexes. Associated to a rhodium precursor, PM-beta-CD-OTPP is able to generate soluble rhodium species in water. In addition, NMR experiments showed that the cyclodextrin cavity remains accessible for a guest even when PM-beta-CD-OTPP is coordinated to rhodium. Finally, this ligand was efficient for rhodium-catalyzed hydrogenation and hydroformylation performed in aqueous medium.